Microbore catheter with velocity reducing chamber

ABSTRACT

A catheter having minimal dead volume due to a &#34;micro&#34; or very small internal diameter for the majority of its length. The distal tip of the catheter, which is the end disposed within the body proximate the location at which the pharmaceutical agent or other fluids are to be delivered, includes a chamber, compartment or other relatively wider internal diameter section, so that the internal diameter rapidly expands in the transitional region between the proximal portion of the catheter (with the very small or micro internal diameter) and the distal portion of the catheter (which includes the catheter tip). The expanding internal diameter causes the velocity of fluid being delivered to decrease prior to its ejection through a distal opening. Also disclosed is a fluid delivery system comprising a stylet lumen separate from a delivery lumen. Separate stylet and delivery lumens permit these different portions of the catheter to be independently constructed to maximize the suitability of each lumen for its intended purpose. The catheter of the present invention may be employed within fully implantable or partially implantable applications depending upon the type of fluid supply device used to introduce fluids into the catheter for delivery to the distal tip disposed at the fluid ejection site.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. patent applicationSer. No. 08/641,185, filed Apr. 30, 1996, now U.S. Pat. No. 5,820,610.

BACKGROUND OF THE INVENTION

I. Field of the Invention

The present invention relates generally to an assembly for deliveringfluids to a desired location within the body; and more particularly,relates to a catheter or similar medical device used to infusepharmaceutical agents or other fluids into the body so that the velocityof the stream of injected fluid at or near the fluid ejection ordelivery site is reduced so as to avoid unintended injury or trauma tobody tissues from the fluid ejection.

II. Discussion of the Prior Art

Physicians today often use a microbore catheter placed to extend to aselected location within a patient's body for both the administrationand receipt of fluids. Microbore catheters are catheters which generallyhave a very small internal diameter along their lengths. Microborecatheters have a unique advantage over other conventional catheters inthat they tend to be more slender, making them easier to use. Ease ofuse is particularly advantageous when catheters are utilized for variousneurological applications. For instance, placement of a parenchymalcatheter near or within the brain for all practical purposes requiresthat a relatively small device like a microbore catheter be used toavoid unintended injury to the brain. (Use of a parenchymal cathetergenerally involves the insertion of a catheter within the brain todispense pharmaceutical agents at a specific desired location; thelocations include the ventricular spaces of the brain.)

It is also generally advantageous for catheters to have a relativelysmaller internal diameter since a smaller internal diameter results inthe catheter having reduced dead volume. Dead volume is equivalent tothe total carrying capacity of the catheter at any given time. Thelarger the carrying capacity the more fluid must flow into the catheterbefore being available for delivery to a site within the patient's body.Thus, minimizing dead volume is important in situations where very lowflows are required to limit delay in delivery of the fluid to thedesired site and in limiting bolusing of small dosages of drugs.

Using conventional microbore catheters to deliver pharmaceutical agentsor other fluids to a desired location within the body, however, has asignificant drawback. While the use of small size catheters can be anadvantage on one hand, the use of microbore catheters also can bedisadvantageous precisely because of their small size. Morespecifically, the small inner diameter of the microbore catheter causesthe fluid to be delivered at a relatively high velocity, particularlywhen the fluid is being supplied to the catheter by manual means, suchas a syringe, or by a drug infusion pump (external or implantable)programmed to provide bolus injections. The high velocity achieved byshooting the fluid through the narrow lumen of the catheter can create aharmful cutting or otherwise traumatizing injury to tissues adjacent themicrobore catheter at the fluid ejection site.

SUMMARY OF THE INVENTION

As explained in more detail below, the present invention overcomes theabove-noted and other shortcomings of prior microbore catheters andmethods.

The present invention preferably comprises a catheter that has minimaldead volume due to a "micro" or very small internal diameter for themajority of its length. In addition, however, the distal tip of thecatheter, which is the end disposed within the body proximate thelocation at which the pharmaceutical agent or other fluids are to bedelivered, includes a chamber, compartment or other relatively widerinternal diameter section, so that the internal diameter rapidly expandsin the transitional region between the proximal portion of the catheter(with the very small or micro internal diameter) and the distal portionof the catheter (which includes the catheter tip). The expandinginternal diameter causes the velocity of fluid being delivered todecrease prior to its ejection through a side or end hole, slit valve,or other such opening, as shown generally in FIG. 1.

In an alternate embodiment, shown generally in FIG. 3, the fluiddelivery assembly of the present invention comprises a stylet lumenseparate from a delivery lumen. Separate stylet and delivery lumenspermit these different portions of the catheter to be independentlyconstructed to maximize the suitability of each lumen for its intendedpurpose. For example, the narrow delivery lumen of the microborecatheter can be made in accordance with the present invention withoutany alteration in the design and construction of the stylet lumen.

The foregoing features of the present invention have been broadlyoutlined in order that the detailed description that follows may beunderstood and so that contributions which the invention provides to theart may be better appreciated. The invention is described in greaterdetail below, with additional features being set forth with reference tothe figures provided and included within the subject matter of theclaims appended hereto.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of the distal end of a closed tipconfiguration of an exemplary microbore catheter in accordance with thepresent invention, depicted in vertical section.

FIG. 2 is an illustration of the microbore catheter shown in FIG. 1,depicted in a cross-sectional view taken along the line A--A in FIG. 1.

FIG. 3 is an illustration of the microbore catheter according to anadditional embodiment of the present invention, having a stylet lumenand a separate fluid delivery lumen, depicted in vertical section.

FIG. 4 is an illustration of the present invention as shown in FIG. 3,depicted in a cross-sectional view taken along the line B--B in FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

Referring initially to FIG. 1, shown is a microbore catheter 10 providedin accordance with a first preferred embodiment of the presentinvention. The catheter 10 generally comprises an elongated tubularmember for delivering fluid to an ejection site within a living body.The catheter 10 includes a proximal end 12 and a distal end 14, whereinthe distal end 14 is disposed at a predetermined fluid ejection sitewithin the body and the proximal end 12 receives fluid from a fluidsupply device (not shown) for delivery to the distal end 14. Thecatheter 10 of the present invention may be fully implantable orpartially implantable depending upon the application. In a fullyimplantable catheter application, both the proximal end 12 and distalend 14 are implanted within the body, with the proximal end 12 coupledto any of a variety of well known implantable fluid supply devices (notshown), including but not limited to an implantable catheter accessport, illustrative examples of which are disclosed in U.S. Pat. Nos.5,137,529, 4,681,560, 5,045,060, 5,399,168, 5,503,630, and 5,637,102, oran implantable drug infusion pump, illustrative examples of which aredisclosed in U.S. Pat. Nos. 4,692,147 and 4,373,527, the teachings ofwhich are hereby incorporated by reference. In a partially implantablecatheter application, the proximal end 12 is located outside of the bodyfor connection to any of a variety of well known external fluid supplydevices (not shown), including but not limited to an external druginfusion pump or a manual apparatus for introducing fluids into theproximal end 12, such as a syringe assembly.

Fluid introduced at proximal end 12 travels through a first lumenportion 16 of catheter 10, having a relatively small diameter. Fluidtravels through first lumen portion 16 to distal end 14 of catheter 10within which first lumen portion 16 continues, defining a continuousfluid passageway, and then terminates. The inner diameter of first lumenportion 16 generally will be approximately 0.015 inches throughout,consistent with the internal diameter dimensions for a microborecatheter.

First lumen portion 16 terminates in distal end 14 at a transition lumenportion 18 with which first lumen portion is in direct fluidcommunication to continue the fluid passageway of first portion 16.Transition lumen portion 18 begins at the termination point of firstlumen portion 16 with an internal diameter identical to that of firstinternal portion 16. The internal diameter of transition lumen portion18 then undergoes relatively rapid expansion of its internal diameterfrom the point at which it meets first lumen portion 16 along its lengthwithin distal end 14 to a point at which it meets a second lumen portion20 having a relatively wide internal diameter.

The internal diameter of transition lumen portion 18 generally will beapproximately 0.045 inches at its distal most end, about equal to theinternal diameter of lumen portion 20. The expansion of the internaldiameter of transition lumen portion 18 of catheter 10 from the internaldiameter of first lumen portion 16 to its expanded internal diameter atits distal-most point generally will be achieved over a relatively shortlength of about 0.30 inches. This preferred length represents a ratio of20 to 1 in comparison with the internal diameter of first lumen portion16.

Transition lumen portion 18 terminates at second lumen portion 20 withwhich it is fluid communication such that second lumen portion 20comprises a continuation of the fluid passageway of the first lumenportion 16 and transition lumen portion 18. Second lumen portion 20 isat the distal most portion of distal end 14 of catheter 10, which asshown in FIG. 1 may be a closed end.

The internal diameter of second lumen portion 20 may be the samethroughout its length, or it may vary (e.g., be tapered) depending uponthe application. That is, it may or may not have the same internaldiameter as at the point it meets transition lumen portion 18.Furthermore, in at least one preferred embodiment, ejection of catheterfluid may take place through a side slit 21 as shown in FIG. 1.Alternatively, distal end 14 may contain a second lumen portion 20 withan end hole, a slit valve or another type aperture or exit opening forfluid ejection (see FIG. 3).

Regardless of the particular apparatus and resulting manner for ejectionof delivered fluid, in view of the foregoing described construction ofcatheter 10, the delivered fluid will be slowed before its ejection fromsecond lumen portion 20 to prevent tissue trauma due to overly rapidejection. The relative velocity of the fluid to be delivered in secondlumen portion 20 (in comparison to its travel velocity in first lumenportion 16) is directly proportional to the ratio of the cross-sectionalarea of the first and second lumen portions, 16 and 20. Thus, by makingthe internal diameter of second lumen portion 20 larger than theinternal diameter of first lumen portion 16, the velocity of fluid insecond lumen portion 20 decreases in comparison with the fluid speedthrough first lumen portion 16.

Rapid fluid speed and relative narrowness are desirable for moving areduced amount of dead volume fluid through first lumen portion 16 totransition lumen portion 18 quickly. Thereafter, however, dead volume isincreased in only a limited way by the relative short portion ofcatheter 10 comprising second lumen portion 20 in distal end 14. Thereduction of speed achieved by the expanded internal diameter of secondlumen portion 20 in distal end 14 slows the fluid being delivered toprevent tissue trauma at the fluid ejection site. Thus, the objectivesof the present invention are achieved.

Although, as shown in FIGS. 1 and 2, a microbore catheter may comprise asingle lumen for delivery of fluid and for channeling of a stylet orguidewire for use in placement of the catheter at the ejection site, itwill be appreciated that alternative structural embodimentsincorporating the present invention are possible. For example, as shownin FIGS. 3 and 4, catheter 10' may include a first stylet lumen 22 and asecond fluid delivery lumen 24. First stylet lumen 22 is of sufficientsize to accommodate a stylet (not shown) for use in extending microborecatheter 10' to the selected location in the patient's body. A typicalinternal diameter of stylet lumen 22 to accommodate a stylet generallyis approximately 0.015-0.030 inches. Stylet lumen 22 may be open orclosed at the distal tip of microbore catheter 10' depending upon therequirements of the particular application involved. Second deliverylumen 24 is in general accordance with the embodiment described abovewith reference to FIGS. 1 and 2, terminating at the distal tip 26 andincluding a transitional portion 28 for slowing the speed of deliveredfluid.

Although the preferred embodiment of this invention has been describedhereinabove in some detail, it should be appreciated that a variety ofembodiments will be readily available to persons utilizing the inventionfor a specific end use. The description of the apparatus and method ofthis invention is not intended to be limiting on this invention, but ismerely illustrative of the preferred embodiment of this invention. Otherapparatus and methods which incorporate modifications or changes to thatwhich has been described herein are equally included within thisapplication. Additional objects, features and advantages of the presentinvention will become apparent by referring to the above description ofthe invention in connection with the accompanying drawings.

What is claimed is:
 1. A catheter, comprising:a generally elongatedtubular member including a first lumen portion having a first innerdiameter, a second lumen portion having a second inner diameter greaterthan said first inner diameter of said first lumen portion, and atransitional lumen portion extending between said first lumen portionand said second lumen portion and having a transitional inner diameterthat expands along its length between said first lumen portion and saidsecond lumen portion such that the velocity of the fluid beingtransported from said first lumen portion toward said second lumenportion will be reduced upon entering said transitional lumen portion,said second lumen portion including a fluid exit opening that isproximate said transitional lumen portion and is substantially open tofluid flow when said second lumen portion is not deformed.
 2. Acatheter, comprising:a generally elongated tubular member including afirst lumen portion having a first inner diameter, a second lumenportion having a second inner diameter greater than said first innerdiameter of said first lumen portion, and a transitional lumen portionextending between said first lumen portion and said second lumen portionand having a transitional inner diameter that expands along its lengthbetween said first lumen portion and said second lumen portion such thatthe velocity of the fluid being transported from said first lumenportion toward said second lumen portion will be reduced upon enteringsaid transitional lumen portion, the length of said transitional lumenportion being approximately 20 times the magnitude of said first innerdiameter of said first lumen portion.
 3. The catheter assembly of claim1, wherein the ratio of said second inner diameter of said second lumenportion to said first inner diameter of said first lumen portion isabout 3:1.
 4. An improved microbore catheter, comprising:a first lumenfor receiving fluid to be delivered to a fluid ejection site within aliving body; a second lumen to be disposed at said fluid ejection sitewithin said living body, said second lumen having an internal diametergreater than an internal diameter of said first lumen; and atransitional lumen extending between said first lumen and said secondlumen, said transitional lumen having an internal diameter that expandsbetween the point of connection with said first lumen and the point ofconnection with said second lumen such that, when fluid is beingdelivered through said first lumen toward said second lumen, thevelocity of said fluid will reduce upon entering said transitionallumen, said second lumen including a fluid exit opening that isproximate said transitional lumen and is substantially open to fluidflow when said second lumen portion is not deformed.
 5. An improvedmicrobore catheter, comprising:a first lumen for receiving fluid to bedelivered to a fluid ejection site within a living body; a second lumento be disposed at said fluid ejection site within said living body, saidsecond lumen having an internal diameter greater than an internaldiameter of said first lumen; and a transitional lumen extending betweensaid first lumen and said second lumen, said transitional lumen havingan internal diameter that expands between the point of connection withsaid first lumen and the point of connection with said second lumen suchthat, when fluid is being delivered through said first lumen toward saidsecond lumen, the velocity of said fluid will reduce upon entering saidtransitional lumen, the length of said transitional lumen beingapproximately 20 times the magnitude of said internal diameter of saidfirst lumen.
 6. The microbore catheter of claim 4, wherein the ratio ofsaid internal diameter of said second lumen to said internal diameter ofsaid first lumen is about 3:1.
 7. A method of reducing the velocity offluid being injected within a living body, comprising:(a) providing acatheter having a first lumen, a second lumen, and a transitional lumenextending in between said first lumen and said second lumen, said secondlumen having a greater internal diameter than said first lumen, and saidtransitional lumen having an internal diameter that expands between saidfirst lumen and said second lumen said second lumen portion including afluid exit opening that is proximate said transitional lumen portion andis substantially open to fluid flow when said second lumen portion isnot deformed; (b) positioning said second lumen at a predeterminedejection site within a living body; and (c) introducing fluid into saidfirst lumen for delivery toward said second lumen.
 8. An apparatus fordelivering fluid to an ejection site within a living body, comprising:agenerally tubular member having a first lumen for receiving fluid to bedelivered to said ejection site, a second lumen disposed at saidejection site for ejecting said fluid into said living body at saidejection site, and a transitional lumen extending between said firstlumen and said second lumen and having an expanding internal diameterbetween the point of connection with said first lumen and the point ofconnection with said second lumen such that fluid being delivered fromsaid first lumen toward said second lumen experiences a reduction invelocity upon entering said transitional lumen, said second lumenincluding a fluid exit opening that is proximate said transitional lumenand is substantially open to fluid flow when said second lumen portionis not deformed.
 9. An apparatus for delivering fluid to an ejectionsite within a living body, comprising:a generally tubular member havinga first lumen for receiving fluid to be delivered to said ejection site,a second lumen disposed at said ejection site for ejecting said fluidinto said living body at said ejection site, and a transitional lumenextending between said first lumen and said second lumen and having anexpanding internal diameter between the point of connection with saidfirst lumen and the point of connection with said second lumen such thatfluid being delivered from said first lumen toward said second lumenexperiences a reduction in velocity upon entering said transitionallumen, the length of said transitional lumen being approximately 20times the magnitude of the internal diameter of said first lumen. 10.The apparatus of claim 8, wherein the ratio of the internal diameter ofsaid second lumen to the internal diameter of said first lumen is about3:1.
 11. A catheter, comprising:a generally tubular member having amicrobore lumen and a velocity reduction chamber, said microbore lumenbeing for receiving fluid from a fluid supply device to be deliveredinto said velocity reduction chamber, said velocity reduction chamberbeing positioned at an ejection site within a living body for deliveringsaid fluid into said living body, said velocity reduction chamber havingan internal diameter greater than an internal diameter of said microborelumen such that said fluid being delivered through said microbore lumenreduces in velocity upon entering said velocity reducing chamber, saidvelocity reduction chamber including a second lumen having an internaldiameter greater than said internal diameter of said microbore lumen,and a transitional lumen extending between said microbore lumen and saidsecond lumen, said transitional lumen having an internal diameter thatincreases progressively between the point of connection with saidmicrobore lumen and the point of connection with said second lumen, saidvelocity reduction chamber including a fluid exit opening that isproximate said transitional lumen and is substantially open to fluidflow when said second lumen is not deformed.
 12. A catheter,comprising:a generally tubular member having a microbore lumen and avelocity reduction chamber, said microbore lumen for being receivingfluid from a fluid supply device to be delivered into said velocityreduction chamber, said velocity reduction chamber being positioned atan ejection site within a living body for delivering said fluid intosaid living body, said velocity reduction chamber having an internaldiameter greater than an internal diameter of said microbore lumen suchthat said fluid being delivered through said microbore lumen reduces invelocity upon entering said velocity reducing chamber, said velocityreduction chamber including a second lumen having an internal diametergreater than said internal diameter of said microbore lumen, and atransitional lumen extending between said microbore lumen and saidsecond lumen, said transitional lumen having an internal diameter thatincreases progressively between the point of connection with saidmicrobore lumen and the point of connection with said second lumen, thelength of said transitional lumen portion being approximately 20 timesthe magnitude of said internal diameter of said microbore lumen.
 13. Thecatheter of claim 1, wherein the internal diameter of said second lumenportion is substantially the same throughout its length.
 14. Thecatheter of claim 4, wherein the internal diameter of said second lumenis substantially the same throughout its length.
 15. The catheter ofclaim 8, wherein the internal diameter of said second lumen issubstantially the same throughout its length.
 16. The catheter of claim11, wherein the internal diameter of said second lumen is thesubstantially same throughout its length.
 17. The catheter of claim 1,wherein the end of said second lumen portion remote from saidtransitional lumen portion is substantially closed to fluid flow. 18.The catheter of claim 4, wherein the end of said second lumen remotefrom said transitional lumen is substantially closed to fluid flow. 19.The catheter of claim 8, wherein the end of said second lumen remotefrom said transitional lumen is substantially closed to fluid flow. 20.The catheter of claim 11, wherein the end of said second lumen remotefrom said transitional lumen is substantially closed to fluid flow. 21.A catheter, comprising:a generally elongated tubular member including afirst lumen portion having a first inner diameter, a second lumenportion having a second inner diameter greater than said first innerdiameter of said first lumen portion, a transitional lumen portionextending between said first lumen portion and said second lumen portionand having a transitional inner diameter that expands along its lengthbetween said first lumen portion and said second lumen portion such thatthe velocity of the fluid being transported from said first lumenportion toward said second lumen portion will be reduced upon enteringsaid transitional lumen portion, and a stylet lumen for accommodating astylet, said stylet lumen being positioned substantially alongside saidfirst lumen portion, the length of said transitional lumen portion beingapproximately 20 times the magnitude of said internal diameter of saidmicrobore lumen.
 22. The catheter of claim 21, wherein said second lumenportion includes a fluid exit opening.
 23. The catheter of claim 22,wherein said transitional lumen portion is proximate said fluid exitopening.
 24. The catheter assembly of claim 21, wherein the ratio ofsaid second inner diameter of said second lumen portion to said firstinner diameter of said first lumen portion is about 3:1.